1. Field of the Invention
This invention relates to curable epoxy resins. More particularly it relates to a novel curing agent, a polyoxyalkylenediamine biguanide salt.
2. Prior Art
Epoxy resins constitute a broad class of polymeric materials having a wide range of physical characteristics. The resins are characterized by epoxide groups which are cured by reaction with certain catalysts or curing agents to provide cured epoxy resin compositions with certain desirable properties. One such class of curing agents is, generally, the amines. The most commonly used amine curing agents are aliphatic amines such as diethylenetriamine, triethylenetetramine and the like and/or polyoxyalkylene polyamines; such as polyoxypropylenediamines and triamines and their amino propyl derivatives.
Epoxy resin compositions having improved physical properties are obtained by employing polyoxyalkyleneamines, and polyoxyalkylenediamines in particular, as curing agents. It is common to employ with such epoxy resin compositions a co-curing agent such as those described in U.S. Pat. No. 3,549,592.
It has been known to form oligomers from aliphatic or aromatic amines and dibasic acids or anhydrides (U.S. Pat. No. 3,732,189). Further diamines have been reacted with maleimides or anhydrides to give elastomers (U.S. Pat. No. 2,818,405). Also, thermosets have been prepared from epoxides and certain carboxyl terminated nitrogen containing compounds (U.S. Pat. No. 3,984,373).
Cured epoxy resin compositions are typically useful as coatings, castings, sealants and especially adhesives.